CVE-2020-16845: Withdrawn Advisory Infinite Loop Vulnerability

HIGH
Advisory Identifier: GHSA-q6gq-997w-f55g
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CVSS 7.5
CWE-835
Published
Advisory Summary

CVE-2020-16845 is a HIGH (CVSS 7.5) infinite loop vulnerability (CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')) affecting Withdrawn Advisory libraries in the Go ecosystem. The issue involves infinite loop in xz. Remediation is available by upgrading affected packages to version 0.5.8.

CVE-2020-16845 at a Glance

CVE Identifier CVE-2020-16845
GHSA Identifier GHSA-q6gq-997w-f55g
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
Affected Product Withdrawn Advisory
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2020-16845

To remediate this vulnerability, upgrade all affected Withdrawn Advisory dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/ulikunitz/xz fixed: 0.5.8 
Upgrade github.com/ulikunitz/xz to 0.5.8
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/ulikunitz/xz

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-16845, inspect your project dependencies for Withdrawn Advisory:

inspect dependencies for github.com/ulikunitz/xz

Analyze the terminal output to locate any version of Withdrawn Advisory in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.5.8), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'), where the product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. In Withdrawn Advisory, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Withdrawn Advisory This advisory has been withdrawn because alerts cannot be issued for the Go standard library at this time. ### Original Description Go before 1.13.15 and 14.x before 1.14.7 can have an infinite read loop in ReadUvarint and ReadVarint in encoding/binary via invalid inputs.

CVE-2020-16845 Affected Withdrawn Advisory Versions

1 component(s)
Fixed Versions:
0.5.8
Product / Package Ecosystem Affected Versions Fixed Version
github.com/ulikunitz/xz
golang/github.com/ulikunitz/xz
Go
< 0.5.8
0.5.8

References

NVD — CVE-2020-16845 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-16845
Withdrawn Advisory Source Repository REPOSITORY
https://github.com/ulikunitz/xz/issues/35
Security Fix Commit FIX COMMIT
https://github.com/ulikunitz/xz/commit/69c6093c7b2397b923acf82cb378f55ab2652b9b
groups.google.com/forum/ WEB
https://groups.google.com/forum/#!topic/golang-announce/NyPIaucMgXo
groups.google.com/forum/ WEB
https://groups.google.com/forum/#!topic/golang-announce/_ulYYcIWg3Q
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2020/11/msg00037.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2020/11/msg00038.html
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6RCFJTMKHY5ICGEM5BUFUEDDGSPJ25XU
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KWRBAH4UZJO3RROQ72SYCUPFCJFA22FO
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TACQFZDPA7AUR6TRZBCX2RGRFSDYLI7O
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WV2VWKFTH4EJGZBZALVUJQJOAQB5MDQ4
Withdrawn Advisory Security Information SECURITY
https://security.netapp.com/advisory/ntap-20200924-0002
Withdrawn Advisory Security Information SECURITY
https://www.debian.org/security/2021/dsa-4848
Withdrawn Advisory Security Information SECURITY
https://www.oracle.com/security-alerts/cpuApr2021.html
Withdrawn Advisory Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00021.html
Withdrawn Advisory Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00028.html
Withdrawn Advisory Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00029.html
Withdrawn Advisory Security Information SECURITY
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00030.html

Frequently Asked Questions

What is CVE-2020-16845?
CVE-2020-16845 is a security vulnerability in Withdrawn Advisory involving Infinite loop in xz under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop').
Which Withdrawn Advisory versions are affected?
Affected versions include releases prior to 0.5.8 across affected packages: github.com/ulikunitz/xz.
What version fixes CVE-2020-16845?
Upgrading to 0.5.8 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/ulikunitz/xz affected?
Yes, github.com/ulikunitz/xz is affected in releases prior to 0.5.8. Upgrade your dependency to 0.5.8 or later.
What is the CVSS score of CVE-2020-16845?
CVE-2020-16845 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2020-16845?
CVE-2020-16845 is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') (The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.).
How can I check Go dependencies for CVE-2020-16845?
Run the dependency tree command: 'inspect dependencies for github.com/ulikunitz/xz'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q6gq-997w-f55g",
  "modified" : "2025-10-14T19:37:19Z",
  "published" : "2021-12-16T19:16:40Z",
  "withdrawn" : "2025-10-14T19:37:18Z",
  "aliases" : [ "CVE-2020-16845" ],
  "summary" : "Withdrawn Advisory: Infinite loop in xz",
  "details" : "### Withdrawn Advisory\nThis advisory has been withdrawn because alerts cannot be issued for the Go standard library at this time.\n\n### Original Description\nGo before 1.13.15 and 14.x before 1.14.7 can have an infinite read loop in ReadUvarint and ReadVarint in encoding/binary via invalid inputs.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/ulikunitz/xz"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.5.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-16845"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ulikunitz/xz/issues/35"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ulikunitz/xz/commit/69c6093c7b2397b923acf82cb378f55ab2652b9b"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/forum/#!topic/golang-announce/NyPIaucMgXo"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/forum/#!topic/golang-announce/_ulYYcIWg3Q"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2020/11/msg00037.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2020/11/msg00038.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/6RCFJTMKHY5ICGEM5BUFUEDDGSPJ25XU"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/KWRBAH4UZJO3RROQ72SYCUPFCJFA22FO"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TACQFZDPA7AUR6TRZBCX2RGRFSDYLI7O"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WV2VWKFTH4EJGZBZALVUJQJOAQB5MDQ4"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20200924-0002"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2021/dsa-4848"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpuApr2021.html"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00021.html"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00028.html"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00029.html"
  }, {
    "type" : "WEB",
    "url" : "http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00030.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-835" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-06-18T22:05:40Z",
    "nvd_published_at" : "2020-08-06T18:15:00Z"
  }
}